U.S. patent application Ser. No. 946,667, filed 12/31/86, allowed but not yet issued (issue fee paid) and corresponding PCT International Application No. WO87/03782, published 7/2/87, disclose triazolinone compounds which exhibit herbicidal activity, at low application rates, against a broad spectrum of grassy and broadleaf weeds. One such disclosed triazolinone compound which is very effective and commercially attractive as a preemergent herbicide in soybeans is 1-[2,4-dichloro-5-(N-methylsulfonylamino)phenyl]-3-methyl-4-difluoromethyl -.DELTA..sup.2 -1,2,4-triazolin-5-one, hereinafter referred to as "Compound A," which has the structural formula ##STR1##
Although soybeans exhibit a tolerance to this herbicide, gramineous crops may suffer harmful phytotoxic effects when the herbicide is applied at rates effective to control undesired vegetation. Typical gramineous crops sensitive to effective weed-controlling rates of application of Compound A are corn, wheat, barley, rice and sorghum.
Compound A can be, and will be, sold with suitable instructions to prevent exposure to sensitive crops. However, measures which increase the tolerance of desirable plants to this herbicide without substantial diminution of herbicidal efficacy against weeds, will greatly expand the applicability as well as the commercial potential of this herbicide.
In this specification the term "crops" includes not only agronomic crops but plants of all kinds, and the term "gramineous" includes both cereal and non-cereal grassy crops, such as corn, wheat, oats, barley, rice, cotton, sorghum, and sugar cane.